Understanding how tumor suppressor gene works will solve how the cell controls its growth and differentiation, how a multi-cellular organism develops from a single cell and how fundamental processes such as transcription is regulated. Subtractive hybridization method will be used to identify physiologic target genes of a tumor suppressor WT1. Identifying genuine targets of WT1 will further our understanding of the mechanism of tumor suppressor genes and provide a foundation for clinical manipulations of this important disease.